This invention relates to a gas burning direct vent fireplace including a room facing sealed glass access door, and having the burner, substantially all of the controls and safety devices mounted on a single removable mounting plate forming the floor of the firebox, and to the mounting and sealing of the glass access door to the firebox.
In direct vent fireplaces of the type illustrated in Wilhoite, U.S. Pat. Nos. 5,471,973 and 5,715,808, and Wade, U.S. Pat. No. 5,782,231, the firebox, i.e., the combustion chamber or housing within which the hot flue gases are generated is disposed within a casing and vents through a conduit directly through an outside wall to the exterior of the building in which the fireplace is located. The firebox receives fresh air which supports combustion from an air inlet conduit in substantially that same exterior location as the exhaust conduit vent and generally concentric with the exterior exhaust vent. Room air is drawn into the front of the fireplace below the firebox, rises above the firebox over the top and exhausts at the front. As the room air flows about and over the firebox, it is heated so that it enters the room as heated air. An array of artificial logs or the like is disposed within the firebox and gas, such as natural gas or propane, may be ignited to create a flame which in conjunction with the logs simulates the aesthetics of actual burning logs.
The front of the fireplace between the location where the air enters from the room and where the heated air returns to the room generally includes an access door having a tempered or ceramic glass in the central area for viewing the flames. In the prior art, the glass access door generally comprises a metal frame disposed about the glass, the frame being sealed to the firebox in the operative position. This frame is generally mounted, as illustrated in the aforesaid U.S. Pat. Nos. 5,471,973 and 5,782,231, using spring biased bolts so that should a gas build-up occur within the firebox and result in an overpressurization or explosion therein, the springs will absorb the force and permit the frame or access panel to react outwardly thereby releasing the excessive pressure and preventing destruction of the glass. Thus, the bolts are for forcing the frame toward the firebox while the springs permit the frame to move away from the firebox.
The sealing of the frame to the firebox must provide a tight fit so as to prevent the flue gases from entering into the room. Elastomeric silicone polymer gaskets have been used in the prior art glued about the glass front, and although these gaskets provide a good seal they do not have very high temperature characteristics. As was pointed out in the U.S. Pat. No. 5,471,973, the silicone gaskets become hard and brittle and age or deteriorate rapidly. It was for this reason that it was proposed in that patent to provide a fiberglass seal about the periphery of the frontal opening of the firebox between the firebox and the glass panel access door, the seal abutting the glass and being spaced from the periphery of the glass panel, and an elastomeric silicone seal fitted about the periphery of the glass without glue was positioned about the periphery of the glass panel to seal against flue gases leaking past the fiberglass seal. In other words, two seals were provided, the first seal being about the periphery of the front of the firebox accessible directly by the flue gases and the access door having a second seal located outwardly of the first seal about the periphery of the glass panel downstream of the fiberglass seal. In the prior art, it should be clear, the gasket wrapped around the glass and provided a seal between the glass and the frame. As aforesaid, the frame itself was mounted to the firebox by the spring biased bolts and thus both the frame and the sealing arrangement was necessary to provide a tight seal and yet permit the frame and glass to move away from the firebox in the event of explosion due to a gas build-up.
Furthermore, in the prior art, the gas burner was generally mounted on a hearth fastened to the floor of the firebox with the controls mounted beneath the floor. With this construction, the hearth must be positioned on the floor and the gas burner mounted on the hearth and connected to the various valve and control elements individually for feeding gas to the burners. This provides a complex mounting assembly, wherein assembly, adjustments, repair and maintenance requires one to work in the limited space beneath the firebox floor between that floor and the floor of the outer housing of the fireplace. Although in the aforesaid Wade U.S. Pat. No. 5,782,231 a partial solution to this problem is disclosed, the limited space beneath the floor still makes maintenance difficult when one must make adjustments or repairs.